Bow mooring



31, 1957 R. w. MOWELL ETAL 3,349,816

BOW MOORING Filed Aug. 18, 1965 4 Sheets-Sheet l R0 er W. Mowell Joan Moscenik Inventors PutenrAfiorney Oct. 31, 1967 R. w. MOWELL ETAL 3,349,816

BOW MOORING Filed Aug. 18, 1965 4 Sheets-Sheet 2 Roger W. Mowell John Mascenik Patent Attorney Oct. 31, 1967 R. w. MOWELL ETAL 3,349,816

BOW MOORING 4 Sheets-Sheet 3 Filed Aug. 18, 1965 Inventors Roger W. Mowell John Mosoenik Porenr Attorney 1967 R. w. MOWELL ETAL 3,349,816

BOW MOORING Filed Aug. 18, 1965 4 Sheets-Sheet 4 Roger W. Mowell John Mascenik Patent Attorney Inventors United States Patent Office 3,349,816 Patented Oct. 31, 1967 3,34%,5516 BOW MQORING Roger W. Moweli, West Caldwell, and John Mascenik, Mount Tabor, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware l iietl Aug. 13, 1965, Ser. No. 483,014 3 Claims. (Cl. 141-387) This application is a continuation-impart of applicants prior copending application Ser. No. 418,646, filed Dec. 16, 1964 and now abandoned.

The present invention is concerned with an improved offshore ship mooring and ship loading structure whereby ships and other vessels can be more efliciently loaded and unloaded, particularly with fluids such as hydrocarbons, gasolines, crude oils, liquefied natural gas, liquefied petroleum gases, such as propane and the like. In accordance with the present invention, a unique structure comprising a caisson or equivalent structure is positioned offshore and utilized in conjunction with a unique type of boom to more effectively moor ships for the purpose of loading and unloading them. The mooring structure of the present invention is particularly adapted to be used in combination with a vessel having the loading manifold at the bow thereof. In accordance with a preferred adaptation, the boom is free to rotate about the structure or caisson as the vessel moves about the structure. A preferred application of the structure is its use for the loading and unloading of tankers, which vessels will be how moored to the caisson. Thus, liquids such as crude oil, gasoline, liquefied natural gas, etc., are delivered to or unloaded from the ships tanks by means of conduits, manifolds, etc., irrespective of wind, current and tide conditions. The preferred structure of the present invention comprises, in essence, a substructure used in conjunction wit-h a revolving boom wherein said boom contains at its outboard end suitable means to convey fluids to and from the tanks of the vessel.

The rapid loading of marine equipment, particularly at offshore sites, with liquid products as, for example, hydrocarbons and the like, has always presented a problem due to the continuous shifting of the marine equipment being loaded. This shifting of marine equipment is due to factors such as tidal variations, changes in the ships draft during the loading-unloading operations and also wave, current and wind action. Thus, there exists the problem of continually adjusting the position of the loading hoses and ancillary equipment to compensate for these continuing and unpredictable changes. Any apprec-iable change or variation in the relative position of the loading hoses, unless corrected, will cause a severe strain on the tanker connections and, in many instances, cause them or the hoses to break, thereby spewing inflammable oil, creating a hazardous condition and putting the tanker out of operation until repairs are effected. This is a very expensive operation.

Thus, whenever possible the vessels are loaded at onshore sites where the vessel may be more securely moored and protected. However, there are many instances where harbors are not available, particularly in areas of the world where it is desired to load and unload fluids, such as hydrocarbon fluids. Therefore, offshore loading facilities must be provided and attending difficulties overcome.

In the case of tankers at piers, wharves and the like, the manifolds of tankers are connected to the pier piping usually by multiple hoses or flexible arms. In the case of marine anchorages, the tanker manifolds are connected to hoses which are usually attached to submarine lines. The number of hoses is limited by the necessity of laying them out on the ocean bottom so that they are not tangled. The hoses must be long, usually 200 feet or more, and the weight, and hence the diameter is limited by the capacity of the ship's gear. Marine anchorages are generally limited to one or two hose connections of 12" diameter or smaller. Tankers are sometimes moored by the bow with hoses extending from the mooring to the bow. However, few tankers have bow connections. On most other tankers, it is necessary either to lay a hose from the bow to the amidships manifold connections or use a floating hose alongside the vessel. The latter is subject to adverse wave, wind and current actions.

The present invention, as pointed out heretofore, covers an improved offshort ship mooring and offshore ship loading stiucture which is characterized in that the ship being loaded or unloaded, as well as the loading boom, will automatically adjust to the composite vector of tide, wind, sea and current as well as compensate for the changing buoyancy of the vessel during the loading or unloading operation. A feature of the present invention is that the arrangement is particularly suitable for the offshore loading of tanker vessels designed to transport liquefied natural gas (LNG) at cryogenic temperature. The cargoes in tankers of this general category are transported in insulated containers and are in the order of 2S9 F. Loading of such cargoes at cryogenic temperature presents serious structural difliculties as LNG at this temperature will embrittle and render inflexible any conventional form of rubber or flexible hose used for a conduit. Accordingly, mooring and loading devices such as shown in the McCammon US. Patent No. 3,093,167 may be unsuitable for the handling of such cargoes in view of the necessity of employing flexible hoses between the end of the loading boom and the moored ship.

In contrast, applicants novel combination described herein employs a loading arm in combination with a fixed pylon structure to produce a novel combination of ship mooring and loading apparatus which is particularly suitable for, although not limited to, the loading of LNG cargoes at cryogenic temperature to a ship having a loading manifold located at its bow.

These and other objects and advantages of the invention will become apparent and the invention will be fully understood from the following description and drawings in which:

FIGURE I is a side elevation view of one form of the invention positioned on the ocean bottom showing the turntable and the loading boom;

FIGURE II is a fragmentary view of the arrangement of FIGURE I showing the fendering system in detail;

FIGURE III is a sectional view taken along line A- A of FIGURE I;

FIGURE IV shows a top view preferred adaptation of the fendering system;

FIGURE IVA is a detailed view showing an alternate form of fendering system employing dampening means; and

FIGURE V is a side elevation view of an alternate embodiment of the invention.

Referring specifically to FIGURE I, a lower base circular or donut ring 1 is shown positioned on the ocean floor 2 beneath the surface of the water 3. Extending upwardly and inwardly from lower base ring 1 are supporting legs 4 and 5 which extend above the surface of the water and are rigidly afiixed at the upper ends thereof to a rigid top platform 8. Two other supporting legs are not illustrated in FIGURE 1.

Extending upwardly from the bottom of lower base ring 1 are a plurality of tendering tubes 9. These tubes extend vertically upwardly and are positioned about the periphery of ring 1. These tubes are preferably hollow and are welded to ring 1 or otherwise suitably attached at the top of the ring and at the bottom of the ring.

These tubes extend to a predetermined point above the level of the water and are attached at the upper ends thereof to a circular member, preferably a box or equivalent girder 12.

In positioning the structure into place, the donut base ring with the fendering rings is placed on the ocean floor. Piling members 13 are preferably driven through each or a selected number of the hollow tubes 9 into the ocean floor. The box girder fendering ring 12 is attached to the upper ends of these fendering tubes 9 and contains inwardly extending radial arms 14 which, in turn, are attached to a flexible or movable top ring 15. The rigid platform 8 supports a turntable mechanism 17 which supports the loading boom. This turntable is of a conventional design. The turntable also supports mooring lines 21 and auxiliary mooring equipment (not shown) such as winches, power equipment and the like (not shown).

A rotating boom assembly St) is rigidly aflixed to turntable 17, which assembly may be of a conventional design. The rotating boom 50 has supporting struts 51 designed to give it mechanical strength and a first arm 52 as well as an opposing second arm 53, both extending horizontally from vertical element which may comprise a supporting strut. A counterweight 54 is positioned at the end of arm 52 so as to stabilize and equalize the weight of the second opposing arm 53 and the equipment mounted thereon.

In essence, the weight of 54 is adjusted so that the moment on one side of the swivel or point of rotation 10 is substantially equivalent to the moment on the diametric other side. It is preferred that arm 52 not overextend ring 12 and that the length of arm 53 substantially overextend ring 12 so as to put the mechanism at the end of arm 53, preferably over the bow of the vessel being handled. Thus the weight of 54 is generally very substantial in order to secure substantially equivalent moments on both sides of the point 141.

A double counterweighted loading assembly 61 is positioned at the end of arm 53. In essence, the loading assembly comprises a loading arm 55 which is substantially counterbalanced by weight 56 and an outer arm 57 which is counterbalanced by counterweight 58. It is evident that the counterweight 56 also counterbalances arm 57 and the ancillary equipment such as hoses, couplings and the like needed to attach the same to the tanker 59, when the outer arm 57 is in the vertical position.

Thus the sum of the moments about the swivel assembly 60 is substantially zero, so that the length of arm 62 and the weight of 56 will substantially counterbalance the weight of arm 55 in any position and the weight of arm 57 and ancillary equipment when arm 57 is in a vertical position. A loading arm assembly which is satisfactory for positioning at the end of arm 53 is described in U.S. Patent No. 3,073,343, issued Ian. 15, 1963 entitled Cargo Loading Apparatus. Inventors: R. W. Mowell ct al. As in the case in the aforementioned patent, it will be understood that the loading arm assembly is capable of horizontal rotation about a vertical axis about a lower swivel bearing 60a.

Thus, in operation, if a ship to be moored nudges against box girder 12 thereby exerting a forward thrust on the girder, this thrust is resisted by bending fendering tubes 9 and the piling contained therein so as to cause ring to move backwardly until the same makes contact with the rigid platform 8. While this distance may vary appreciably, it is preferred that the same be from about 1 to 30 feet.

This method of attaching the radial arms from top ring 15 to box girder 12 is more clearly illustrated in FIGURE II wherein similar elements described in FIGURE I are similarly numbered. Referring specifically to FIGURE 11, fendering tubes 9 are shown attached to box girder 12. Box girder 12 is securely attached to top ring 15 by means of radial arms 14a, 14b and 140, both top ring 15 and the rigid top platform 8 are positioned below working platform 16. Working platform 16 is attached to rigid top platform 8. The working platform 16 is supported by suitable means. A vertical feed line 19 is shown extending from shore line 18. While only one shore feeding line 18 and one vertical feed line 19 are illustrated, it is to be understood that a plurality of lines may be utilized carrying different fluids, utilizing a special swivel arrangement to allow passage of the separate fluids through the turntable section 17.

FIGURE III is a vertical view through AA of FIG- URE II. The inclined supporting legs 4, 5, 6 and 7 are shown rigidly attached to the lower base ring 1 and the shore feeding line 18 is shown in communication with the vertical feed line 19. The fendering tubes 9 are shown extending vertically upwardly from the lower base ring 1.

FIGURE IV illustrates a preferred method of connecting movable ring 15 to girder 12 in order to secure maximum mechanical strength. Strut 14a is substantially perpendicular to the respective rings while struts 14b and are connected diagonally. A plurality of support struts 23 are also employed to brace platform 8 to platform 16. Referring specifically to FIGURE IVA, a desired modification is shown wherein springs 25 are shown positioned between rigid platform 8 and flexible ring 15. Thus as girder 14 is pushed inwardly by a vessel, this movement will be resisted by the springs resisting the movement of flexible ring 15. Thus, as the vessel is being loaded or unloaded it will swing about the periphery of the structure, depending upon wind and wave conditions. As the vessel swings around the substructure, the turntable will rotate along with the structure, thereby eliminating any tension or undesirable thrust on the loading conduits and lines.

In the embodiment of the invention shown in FIG- URE V, a vessel such as an LNG tanker 151 is moored to a pylon structure similar to that of FIGURE I by means of a mooring line 121. Each of the elements of the pylon structure is similar to that of FIGURE I and have been designated with like reference numerals. A preferred adaptation of the embodiment of FIGURE V is to have the outwardly extending arm 152 terminate at a point radially shorter than the periphery of the fendering ring 12. Unlike the previous embodiment described, the embodiment of FIGURE V has its counterweighted loading arm mounted directly on top of the platform 17 with the axis of rotation of the loading arm coincident with the axis of rotation of the turntable 17. The loading arm includes an inner boom 126 connected through swivel 129 to the upper end of an outer arm 130. The outer boom 130 is shown in a substantially vertical position and is connected at its lower end to a fixed bow manifold 153 mounted on the vessel 151. The lower elbow structure shown generally at 131 includes swivel flanges 154, and 156 to allow respectively for pitching, yawing and rolling movement of the vessel.

A counterweight 128, acting through a boom arm 127 along with a second counterweight 136 and its associated arm 1335 act in the aforesaid described fashion to keep the inner boom 126 and outer boom 130 in substantially static equilibrium irrespective of their relative orientations with respect to gravity. An upstanding portion 122 of the shore line 18 and vertical feed line 19 is connected to the boom 126 conduit through a suitable swivel connection 157. In this embodiment of the invention, it should be noted that by virtue of the mounting of the loading arm assembly with its pivotal axis coincident with the axis of rotation of the turntable 17 that it is free to swing with the vessel 151 in simplified fashion as the ship weathervanes about the pylon structure.

While in the preferred application of the present invention the cargo conduits 18, 19 and those running through the inner-outer booms of the loading arm will preferably be insulated to maintain the LNG at a low temperature,

those skilled in the art will readily appreciate that the invention may be used to equal advantage in the bow loading of cargos of more conventional character. However, an important feature of applicants novel combination is that it permits the loading of LNG cargos at cryogenic temperature to a fixed manifold located at the bow of a vessel directly from an oitshore mooring without the need for passing any of the LNG cargo through a flexible hose connection. This is accomplished by the fact that all of the movable connections of applicants arrangement are of metallic construction not relying upon the flexibility ot a length of hose for providing pivotal freedom.

While specific embodiments of the invention have been shown and described in detail, to illustrate the application of the inventive principles,iit will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In combination, a ship and mooring structure for transferring a liquid cargo at cryogenic temperature to and from said ship; said ship having a rigid manifold connection attached to its toredeck and being free to rotate about said mooring structure without the passage of the liquid through flexible hoses; and a mooring structure, said mooring structure including a lower base donut ring adapted to be positioned on the ocean floor, supporting legs aflixed to said donut ring and extending upwardly and inwardly from said donut ring to a point above the surface of the water, a top rigid platform supported above the water by said supporting legs, tendering tubes extending upwardly from said donut ring and positioned about the periphery of said donut ring to a point above the surface of the water, a tendering ring rigidly attached at the upper ends of said tendering tubes, a top ring positioned within and above said tendering ring and rigidly attached to said tendering ring by means of structural members, said top ring being positioned about said rigid top platform, a turntable mechanism positioned on said rigid top platform and adapted to rotate with respect thereto, a first arm extending horizontally outwardly from said turntable mechanism, a second arm extending outwardly from said turntable mechanism and diametrically mounted with respect to said first arm, a loading mechanism positioned on the outboard end of said second arm and pivotally supported for horizontal rotation with respect thereto, a first counterweight positioned on the outboard end of said first arm, the weight of which is to produce substantially equivalent moments of said first arm and of said second arm and loading mechanism; said loading mechanisms including an inner rigid conduit pivotally connected through a swivel coupling to a support base, an outer rigid conduit pivotally connected through a swived coupling at one end to the inner conduit and at its opposite end arranged to be directly fastened to the rigid manifold on said ship, insulating means about said inner rigid conduit, and said outer rigid conduit, a second counterbalancing means to substantially counterbalance the inner conduit and, a third counterbalancing means being mounted for rotation relative to the outer conduit and rotatable in response to the movement of the outer conduit from a vertical position to change its movement arm in a direction and an amount to substantially counterbalance the outer conduit as it moves from said vertical position whereby said cryogenic liquid cargo may be transferred to and from said ship exclusively through insulated rigid conduits.

2. Structure as defined by claim 1 wherein said first arm terminates inwardly of said tendering ring and wherein the length of said second arm overextends said tendering ring.

3. Structure as defined by claim 2 wherein said turntable contains means terminating inwardly of said fendering ring and adapted to receive a mooring line from the bow of said vessel.

References Cited UNITED STATES PATENTS 785,518 3/1905 Parsons 212-48 2,650,180 8/1953 Walker 137-375 3,073,343 1/1963 Mowell 137615 3,086,367 4/ 1963 Foster 9--8 X 3,093,167 6/1963 McCammon 141--387 3,120,106 2/1964 Foster 6146.5 3,221,771 12/1965 Dollinger 137--615 FOREIGN PATENTS 692,892 6/ 1953 Great Britain.

WILLIAM F. ODEA, Primary Examiner. ISA-DOR WEIL, Examiner. H. W. WEAKLEY, Assistant Examiner. 

1. IN COMBINATION, A SHIP AND MOORING STRUCTURE FOR TRANSFERRING A LIQUID CARGO AT CRYOGENIC TEMPERATURE TO AND FROM SAID SHIP; SAID SHIP HAVING A RIGID MANIFOLD CONNECTION ATTACHED TO ITS FOREDECK AND BEING FREE TO ROTATE ABOUT SAID MOORING STRUCTURE WITHOUT THE PASSAGE OF THE LIQUID THROUGH FLEXIBLE HOSES; AND A MOORING STRUCTURE, SAID MOORING STRUCTURE INCLUDING A LOWER BASE DONUT RING ADAPTED TO BE POSITIONED ON THE OCEAN FLOOR, SUPPORTING LEGS AFFIXED TO SAID DONUT RING AND EXTENDING UPWARDLY AND INWARDLY FROM SAID DONUT RING TO A POINT ABOVE THE SURFACE OF THE WATER, A TOP RIGID PLATFORM SUPPORTED ABOVE THE WATER BY SAID SUPPORTING LEGS, FENDERING TUBES EXTENDING UPWARDLY FROM SAID DONUT RING AND POSITIONED ABOUT THE PERIPHERY OF SAID DONUT RING TO A POINT ABOVE THE SURFACE OF THE WATER, A FENDERING RING RIGIDLY ATTACHED AT THE UPPER ENDS OF SAID FENDERING TUBES, A TOP RING POSITIONED WITHIN AND ABOVE SAID FENDERING RING A RIGIDLY ATTACHED TO SAID FENDERING RING BY MEANS OF STRUCTURAL MEMBERS, SAID TOP RING BEING POSITIONED ABOIUT SAID RIGID TOP PLATFORM, A TURNTABLE MECHANISM POSITINED ON SAID RIGID TOP PLATFORM AND ADAPTED TO ROTATE WITH RESPECT THERETO, A FIRST ARM EXTENDING HORIZONTALLY OUTWARDLY FROM SAID TURNTABLE MECHANISM, A SECOND ARM EXTENDING OUTWARDLY FROM SAID TURNTABLE MECHANISM AND DIAMETRICALLY MOUNTED WITH RESPECT TO SAID FIRST ARM, A LOADING MECHANISM POSITIONED ON THE OUTBOARD END OF SAID SECOND ARM AND PIVOTALLY SUPPORTED FOR HORIZONTAL ROTATION WITH RESPECT THERETO, A FIRST COUNTERWEIGHT POSITIONED ON THE OUTBOARD END OF SAID FIRST ARM, THE WEIGHT OF WHICH IS TO PRODUCE SUBSTANTIALLY EQUIVALENT MOMENTS OF SAID FIRST ARM AND A OF SAID SECOND ARM AND LOADING MECHANISM; SAID LOADING MECHANISMS INCLUDING AN INNER RIGID CONDUIT PIVOTALLY CONNECTED THROUGH A SWIVEL COUPLING THE SUPPORT BASE, AN OUTER RIGID CONDUIT PIVOTALLY CONNECTED THROUGH A SWIVED COUPLING AT ONE END TO THE INNER CONDUIT AND AT ITS OPPOSITE END ARRANGED TO BE DIRECTLY FASTENED TO THE RIGID MANIFOLD ON SAID SHIP, INSULATING MEANS ABOUT SAID INNER RIGID CONDUIT, AND SAID OUTER RIGID CONDUIT, A SECOND COUNTERBALANCING MEANS TO SUBSTANTIALLY COUNTERBALANCE THE INNER CONDUIT AND, A THIRD COUNTERBALANCING MEANS BEING MOUNTED FOR ROTATION RELATIVE TO THE OUTER CONDUIT AND ROTATABLE IN RESPONSE TO THE MOVEMENT OF THE OUTER CONDUIT FROM A VERTICAL POSITION TO CHANGE ITS MOVEMENT ARM IN A DIRECTION AND AN AMOUNT TO SUBSTANTIALLY COUNTERBALANCE THE OUTER CONDUIT AS IT MOVES FROM SAID VERTICAL POSITION WHEREBY SAID CRYOGENIC LIQUID CARGO MAY BE TRANSFERRED TO AND FROM SAID SHIP EXCLUSIVELY THROUGH INSULATED RIGID CONDUITS. 